Block molding machine and process



3 Sheets-Sheet 1 M. CLARK ET AL BLOCK MOLDING MACHINE AND PROCESS INVENTORS.

MORTON. CLARK y FRANK PR/EsTLY ATTORNEYS 1950 M. CLARK ET AL March 28,

BLOCK MOLDING MACHINE AND PROCESS Filed Set. 5, 194:;

3 Sheets-Sheet 2 INVENTORS. MORTON CLARK FRANK C. PRIEsTLY ATTORNEYS March 28, 1950 M, CLARK ETAL 2,502,075

BLOCK MOLDING MACHINE AND PROCESS Filed Sept. 3, 1946 3 Sheets-Sheet 5 I INVENTORS. P MORTON CLARK Fig I 3y FRANK C. PRIESTLY ATTORNEYS Patented Mar. 28, 1950 STATES; FATE ()FF BLOCK MOLDING MACHINE AND PROCESS Morton Clark," Seattle; and Frank C; Priestly,-

Edmonds; Wash;,.. assignors: to. United States: -Loc.:-Blo.c:Corporation, Seattle," Wash., a corpo ration ,of; Washington AhplicatibnSptbmbBrB, 1946; Serial No. 6943582 13;Glaimsn (CI. 2557) 15, 1925. Some-whaflsimilar-"blocl s:are disclosed-f in the patent'to R'obert*D.= Wells; No: 23713201,, datedMarch 13, 1945? p Ordinarily in the" construction of concrete building units- -some-variation'dn dimensions l5v permissible, that "is-' 'to'say; the tolerance is f airly wide, for the normal allowance-for mortar spa-ca can absorb any such variation: With-"such'blocks as are illustrated in ei-therrWellspatent, however, which are'laid'up; without mortar, and which interlock by the' interfitting ribs'and grooves; orlugs and sockets; each'rblockmustbe"of"precise* dimensions, within; a very; small. tolerance. Otherwise, there, will'jbe'cracks "between" a'dj oinin'g units, and the projecting ribs will not properly;

fit within thegrooves. that are intended to receive them, hence the blocks'willhot'lie in straight courses, nor will they, mutually support one another, as is intendedll i i Very considerable. difli'culty, has been en: countered. heretofore, in .molding. blocks of i this. type with thecnecessary,degreeMofgprecision.- The: blocks must be produced at a rapid rate, in order: that. their cost may, beskepi; ,low, and int-so, pror ducing them, ithas been found tdifliculttolmaintain their; accuracy-within .the. required tolerance. Wehave:discovered.thattthealack: of 1- accuracy isnot due :to; asfaultIin .thamold bOXgf'DOI inthes molding process, nor, iseitl due totlaclciot accuracy; inithes construction offv parts, but arises-from; the: f act :1 that- 1 in: the-a; compressing, operation as cei am part: :of; thecair which: .p.ermeates:-@the= enstiresbloc-le, iS;'. t1,"&PQ$dJ:-Within the block and i isv unavoidably compressedtherein; 1 with: the ,resultt 45 that: when: tlieupressuree' isfrell'eased; preparatory tot-discharger oi L the: compressed butiiunsettblocka. from-the mold-b022,":thetainthus compressed-tends": to expand again, and thIlS-ZIiIICI GBJSESBthBfZSiZEZOi-il or: distortathe bl ocleatithatzpointtat": whichthe 5O compressed air released; Brimarily, the-: diiiicultyliesswith. eentraprnent of "arsmall, residue. 0t: air: and -itsircompressionr withirrzthez; block, followedtlb flrst releases of?" he s-pressure z intaismai li area; giui'nglirismtoctheedistortion ed? @{p the block in the'vic-inity of tlie-iportionfirst uncovered.

Accordingly; it'isone" of the primary objects of'the.presentinvention to devise a process, and? mechanism for carrying out the same, by means of which expansion" of th'e-=-entrappediand compressed air is so controlled that it will not-disturb the ultimate size orshape oftlie block, but will' leave it, when thepressureis fully released, in exactly the intended shape and size;

It is, of course, also-an objectto' provide a" practical. machine and a methodof molding" blccks'loy which such blocks can be=molded expeditiously and cheaply, starting with loose concrete mixture andlending in a compressedbloclc of-exact andun'iformdimensions; which can be carried away for curing:

In such a process-ashas been sketched' im mediately abova it becomes necessaryto handle :the' block as' it is delivered from the mold box,

immediately"afterit'has been compressed;- and long before it has-'acqui-red any' set; Moreover,

since the most practical way of discharging sucha block from the mold is to open the-mold-boxand permit the block to be delivered by gravity, this has-the serious drawback that such anun set but compressed block is likely to be disturbed,

particularly in the region-of the projecting ribs" and the grooves; if it is permittedto drop by even a fewthousandths of'an inch relative to the die plates by which it is formed. In consequence, one of the additionalimportant objects of the present invention is-to provide-a process and a machine for" carrying out the-same; by which such blocks maybe contacted very pre-' cisely by a pallet or the like; applied'to'its bottom immediately prior to-the opening of the-mold box, to the-end thatthe block may besupported in situ untilithemold' b'o'x'has opened widely enough to permit the bl'ockto 'clear'al-lparts of the mold box, and only then to stripthe mold box' parts from-"the'block:

thousandths of an: inch in such places and operations where" such extreme accuracy is 'desirableh With these and other objects in mind, as will appear hereafter, the invention comprises the novel process and the novel machine for molding concrete blocks or like products, as shown in a typical form in the accompanying drawings, as described in the specification, and as will be made clear by the claims which terminate the same.

In the accompanying drawings the machine of the invention is shown in a typical and operative form, but it will be understood that the details thereof, and the detailed arrangement of the parts relative to one another, may be varied within the scope of the appended claims.

Figure 1 is in general a top plan view of the machine, with various parts omitted or broken away, and Figure 2 is in general an end elevation of the same, broken back generally as indicated by the line 2--2 of Figure 1.

Figure 3 is a detail cross section taken on the line 3-3 of Figure 1.

Figure 4 is in general a side elevation, with parts broken back and shown in section.

Figures 5, 6, 7, and 8 are successive diagrammatic showings, illustrating the cycle of operation.

According to the present invention a mold box is made up of a front die plate I, a rear die plate 2, both of which are shiftable, and a fixed mold cavity liner having end plates I I and a connecting bottom I4, which rests upon a fixed table 39. A reciprocable yoke It] carries the front die plate I. The rear die plate 2 is carried by a yoke 2b, which is movable with and also with respect to the front die plate I. Such a mold box is open at its top, and in its discharging position is open at its bottom, and at its ends. One of the die plates, as, for example, the die plate I, is formed with ribs I2 which define grooves in the molded block, while the other die plate, as 2, has complemental depressions 22 by which are formed upon the block projecting ribs which are intended to be received in the grooves formed by the ribs I2, but in blocks of the course above, when. the block is laid up in a wall.

By substituting one liner II, M for another the one mold box can turn out different sizes of block. When the liner is replaced, a different set of die plates I, 2 must be used, for these dies fit closely the liner II, I4, and the die plate 2, at least, slides between the end plates II and over the bottom I4.

The yoke I0, it will be observed, extends to the opposite end of the machine, and is guided at I3 in the frame 3 for sliding movement in a generally horizontal plane with respect to the frame. The yoke may be considered as carried by and movable with the yoke IE, but it is guided thereon at 23 for such movement relative tothe yoke It as may be necessary to effect compression approach and then relaxation or recession of the die plates I and 2.

The mold box, constitutedby the die plates I and 2 and the liner II, I 4, is open at its top. It is adapted to be placed in registry in one position with a hopper 4, supported upon'the frame and terminating in a position to register with the mold box when the movable parts of the latter have been withdrawnto charging position. During such registry the-mold box is filled with loose concrete materialin a rather dry mix. The bottom of the mold box is closed at such time by the liner bottom I4, resting upon a table 3!], which in effect is a part of the fixed frame. The mold box, or at least thedie plates I and 2 which constitute an important part thereof, is shiftable 4 from this charging position outwardly beyond the table 3% and liner II, I4 to a discharging position, and the ensuing movement of the block, supported only by the die plates I and 2, trowels the remaining surfaces as it passes the liner II, I I. Some means must be provided to close the top of the mold box during compression of the charge, and to prevent discharge of material from the hopper 4 when the mold box dies I and Z and the intervening block are displaced beyond the liner I I, I5. Such a means may take the form of a closure plate 40, which may be drawn aside to admit material to the mold box from the hopper, or which may be projected forwardly to cut oil. communication between the two. The plate is guided at 4|, in effect in the fixed frame, to permit such movement to and fro. In the closed or non-communicating position of the closure plate it not only closes the bottom of the hopper, but also the top of the mold box.

In order to receive the block when compressed, and to move it in such manner as to clear the projected mold box parts so that the latter may withdraw for receiving a fresh charge, and in order that this operation may be accomplished with sufficient rapidity, and yet without the likelihood of damaging the compressed but unset block, such as would occur if it were permitted to drop, there is provided a platform or palletlike arrangement, indicated at 5, which is carried upon a carriage slidably guided at 5| in the frame for substantially vertical movement. The pallet 5 is so positioned that it is directly beneath the projected position of the mold box, that is, the discharging position beyond the edge of the table 35. .Means are provided to effect proper and timed movement of the pallet 5 into position to receive and hold the compressed block in situ, and at that moment to open the mold box to release the block, and then to drop the pallet, or otherwise move it with its compressed block out of the way of the mold box parts for return of the latter to charging position.

The description of the controlling mechanism for all the parts so far described has been omitted heretofore, because, for one reason, various mechanisms suited to the ends in view might be designed, and the particular mechanism in the drawings is to be taken primarily as illustrative, although it is operative and practical. Then, too, it is necessary to a thorough understanding of the control mechanism that the general operation and functions of the controlled parts be first understood. I

Proceeding, then, to a description of the control mechanism, it will be observed that three cams 6, I, and 8 are fixed upon a common rotative shaft 3 I, which shaft is driven through suitable gearing 32 from a drive pulley 33 or other means connected to a suitable power source. The cam 6 reciprocates the yoke I0, and thus effects shifting of the mold box die plates I and 2 between the charging'and the discharging positions. The cam 7 controls the "compressive movement and the reverse relaxing and releasing movements of the die plate 2 relative t'o'the die plate I, and the cam 8 controls the movement ofthe closure plate 4!]. The cam 6, in addition, controls the vertical movement of the pallet 5.

The cam 6 contains a groove within which is'received a cam follower roller BI upon an arm 62 pivoted in the frameat 63 near its lower end, and connected at its upperend at 64' directly to a side arm of the yoke jI0. "The'yoke 20, in addition to-bei'ngguided at 23"upon the yoke I0, is

52 joined: to; the: latter: to: more: wlthithee yoke 1 I0? byrazrz togglealike a arrangement; consistingqof; th. links" 24'. and: 25%; carrying: a; roller: 26' at; tiiei commonpivot: Theelink-ifli iszpivotedcait. 26 :tor:

the: yoke: 20, and, therlinlnc25 is:'pivoted-.at ;'2l to:- a;

the yoke'aI 0: Opposed stops-28. and;28f,z.adjustablee in a: forked. end 29i'ofithe link-25', may: engage with; the yoke? I 0-. to limit :the extent :of pivotali movement; or: the: link: 25'; and consequently to";

. limit the relative movementtof the yokeflflu with follows I the. rim-.80 of :thevcamrand zeffectsacorre we sponding movement; of the: closure: plate;=; 401s througharcompositerodAZvincorporatingvacsprihm 431 which. permits? the. rodzto yieldw inacthez exentr, the closure:-=plate:40: becomesistuck; orrencountersr;

an unyieldingobieet such asraa'.piececoiigravel;v

A cam-zfollowerrr52'zupon: a .bEII/CI'BJIIKZIGVGBX 53 5i pivoted. at 54iin-thetframe bearsr upon themoute 3 edge ofv the cam'iB,- .andrtransmits: :motiontby wayiof a link-.55; 1e-ver;-5'6-=; and din-1:151 :tothescarria'ger.

50, to control-itsmoyement; Verticadimovementzz.zen.

of the; carriage: isE effected l in opposition; to: the cam 6-L-by -a counterweight 5-8 ortrthe like:

The earn 8 I acts-primarily torclosezthee closure plate 48, and. opening thereof: is 'accomplishedzbyc spring mechanism,,part: ofrwhiclin is illustratedil';

in detail-inxFigureiz-iii Theeheaidzfl isrconnecte by a rod 45; toa-theframe, and a: similar;:head-i46'- is connected by a: sleeve'r tl to theaclosureeplateie. 49. The sleeve 41:is slotted forethenprojectio of arms 48, byvwhich-the-head:44wisiconnecte to the internal, axially: disposed'arodilia Aicome pression :spring 494s edisposed betweemtheeheadst; 44 and 46'. Outwardor-closingrmovementi.of.thes closure plate 40 causes approache thee headiif 46 r to the fixed? head: 44, and-.- consequent; come I i mold box haszbeen returned to theicharginggposi-e- {wrtion, in reg-istrywithztheehopper' 4;-

It will bezrealized inexamining. Figures: 6;,7' and 8 rthat,. 'oecause oi the. diagrammatic layout it. is necessary to distort certain elementsiiromitheirr proportionsandrelationshipeshown :in (then-other as figures However, itv isbelieved that-:such. dia.- grammatio showings are necessary; to make clear; the cycle and.sequenceofoperations; sinceit-pere mits the three cams: 6-, I, and ,S -tebe-spread out;1. to beshown ina single.-plane,.,though: actually; theyare coaxially aligned, ina threeis separates;

planes... 7 I

Figures; 5, shows. them chargingeQnera-tiorr; Tlh'et mold ,boxlpartsri .and z, carried 'by theirxrespec tive. supporting Yokes I hand; .Zflg-y, areew-ithdiaw, I I to. and... spreadapart iWi-thill': at chargingspositio beneath. the; throat of. the. hoppen-z l a-ndnthe closure. plate. 40.. hassbeen i opened: by; expansion of-the spring 49:. The; die. platesa l. ..-:an d.i.2-. are?- widely separated,.beoauseetheatoggle links: are broken-textilesmaximum. extent; an thepallet. has:- been withdrawn downwardly; .welljl clear ofstheelevelwo-f. the zmoldabox, .toxenablezreeimoval ot-a; previously rcompletedablocki: Theecam...

follower: 6i, controlling; the -.position of; thegmoldt? 6 boxszhasza entered: an. appreciable: low dwelli'. 65.; offthe cam-.6 IThe-cam followerr52 isrpart-way throughpand extended high dwell 665 upon the. exterionof; cam-4'61. The camfollower 26,,which":

.controls, the. toggle links 24, 25,- has just. com

pleted: riding 'along: -.a low dwell 14 of; the; cam I. Thescam follower iileispart way through a high: dwell 84.:

Whenvthen'equisite charge has been received.

within: the. moldxbox the closure plate 40 iSClOSEdJE and the; spring 49* is compressed by the'portion 8540f the1 cam* i3; and now, as seen in FigureGi; thelcamiollower BIis entering a low dwell-81. This holds the closure plate 413 closed, andthei spring. 49';-cornp1'essed. At the same time the CamZf0l10W1"2.6 :h'as ridden up the rise II of the. camri torazdwell i'ththe efiect of which is to ad.- vance the die plate? toward thedie plateI by: aligning-thetoggle links24, 25. The efiect of;

theaapproach of; the die plate 2 toward the die plate I 'is'torcompressthe'charge received within; thermold'rbox; and it isof importance in this cone nection: that, the 1 compression so. accomplished. be; somewhat cirriexcess: of that required tocom:

pressrthefiblock to its ultimate dimensions, and; occurvonly-aiter closure of the closure plate 40...

If; for-example, the block is to be six inches high, and-.isrbeing molded fiatwise or on its side, it may beesupercompressed to six inches minus thirtythousa-ndths; bytheadvance of the-dieplate 2"v toward'the die.- plate in..the-manner indicate in Figure 6.

But. there ensues immediately relaxation of the mold'box,".or"separa-tonof the die plates land]; ,2 .by an extentsufficient te permit the:.-charge so.

supercompressed. to expand again, but. only-- slightly-and: uniformly; namely, to the ultimate:- dimensions of theblock. Such relaxation avoids anyttendency for the block to swell in the region i first uncovered; say by the plate 40, and reverses any such tendency by distributing the expansive tendency throughoutthe entire block, while it is stilllconfinedi. Since this'relaxation can be ac-- companied by projection of the mold box toward: thedischargingposition, the relaxation is effected by' 'the" action of-the cam 'i'tupon thecam follower 26', tending to: and actually slightly break ingajthealignment oithe toggle links 24 and 25', but :atlthis time the die plates and'the mold box: as'a.wholeare -being-advanced or projected outwardly'," and so the cam follower 26 is received b'etweenathe horizontally disposed fixed guides 31 (see Figure 7) which limits the extent of this breaking-ofthetoggle links 24 and 25. Meanwhile-thezcam follower 6i, rising at 61, translates thexmoldzbox bodily (minus the liner I I, M) to thezleft, ortoward the discharging position, for; itzwil-Lbe remembered, the die plate 2 is moved.

Thercamfl however, does not any; other .wise controlmovementeot the dieplate 4 In. addition; .-.as the.;mo.ld box has been; moving:

highdwell 66 to the low dwellat 68.

At such :time as. the; follower 2t clears the -=left end ,of the fixed. guide 3 which condition is.il1us.-- tratedzin :Figure: 8, thetoggl'e links 24 and25f may relax fully, and do so, and effect full release ofi thesblockr byi'etracting the die plate 2. relative to,z=the:.die-.p1ate-: I.- The. compressed :blockawould dronmponztheepallet- 5 when-this. occurs, were-wit:

7 ndt for the fact that this pallet, which previously has been brought into close proximity to the open bottom of the mold box, is just prior to this time moved upwardly the remainder of the way to contact with the lower surface of the block, and to support the block. The means by which this is effected will be explained later, but it is an important part of the process that the block is not permitted to drop when the mold box opens, but is held supported in situ until such time as the mold box is fully opened and the block can be withdrawn from within it, without contact between the block and the mold box, or any part thereof.

Shortly after the pallet has been moved downwardly, that is, after a time sufiicient to permit the block to clear the mold box completely, the follower 6i reaches the portion 59' of the cam 6, and the yoke ill, carrying the die plates l and 2 in their completely open position, is retracted toward the position of Figure 5. In so do ng the cam follower 26 moves below the fixed guides 3! beyond the right hand end thereof, so that parts eventually reach the position of Figure 5. When the mold box has again reached the charging position the cam follower Bl reaches the portion 88 of the cam 8, which permits the spring 49 to expand and quickly to withdraw the closure plate 40, whereupon a fresh charge enters the mold box. Parts are now in the position of Figure 5, and a cycle has been completed. The same cycle can be repeated over and over again.

Upward movement of the pallet 5 under the influence of the weight 58 and as regulated by the cam 6 is limited by a stop 59 on the carriage 50, which may engage a slidable stop 9. This stop 9 is supported upon the frame 3, and is urged to the right, as viewed in Figure 4, by an extension spring 90. t is provided with an upstanding end at 9|, which may be engaged by a pin 92 upon the yoke 26, as the latter moves to the left or toward the discharging position. The pin 92 is so positioned with respect to the upstanding end 9| that it engages the latter in the last fraction of the movement of the mold box toward discharging position. Such engagement moves the stop 9 to the left, and permits the stop 59 to rise within the notch 9' of the stop 9, which in turn permits slight upward movement of the pallet 5,

and the parts can be arranged with great accuracy so that the pallet 5 will just contact the exposed bottom of the compressed block as the latter reaches its discharging position, and prior to any opening movement or release of the block from the mold box (other than the relaxation already mentioned) Such release immediately ensues, however, and thus the block is left in situ upon the pallet, whereupon the pallet drops to move the compressed block clear of the mold box, and then the latter is retracted, as has already been explained.

The relaxation of the mold box, following com pression and prior to release, is an important el'e-' ment of the present invention. Such relaxation need be only a few' thousandths of an inch; but is" sufficient to permit the entrapped air, which has been compressed, toexpand again, but during:

This movement may be in the nature of a few thousandths, say thirty-thousandths, of an inch, but thereby the bottom of the block, already compressed, does not have to slide over a fixed pallet, nor yet to drop and risk break-up, nor damage to the necessarily accurate ribs and grooves; the pallet merely contacts the block and holds it where it was while the mold box is stripped or withdrawn sidewise from the compressed block.

We claim as our invention:

1. The process of molding concrete blocks or like products which comprises charging a mold box, compressing such charge therein to less than the intended block size, relaxing such compression to the intended size, maintaining such relaxed compression during a predetermined short interval, and delivering the compressed product from the mold box.

2. Those steps in the compression molding of concrete blocks or like products, which comprise compressing the block to a size less than the intended size, promptly relaxing such compression to the intended size, on at least one side of the block, and during a predetermined short interval, to allow uniform slight expansion of the block during such interval, and removing compression completely on another side of the block at the end of such interval following such expansion of the block, whereby the expanded block may emerge undistorted at its intended size.

3. A machine for molding concrete blocks or like products, comprising a fixed mold box bottom, a charge-conveying chute terminating thereabove, a front and a rear die plate and side plates cooperating with said bottom to form a mold box, said front and rear die plates being guided for conjoint movement between a charge-receiving position,resting upon said mold box bottom and in registry with said chute, and a discharging position beyond said mold box bottom, and being also relatively movable, a block-receiving means at the discharging position, a closure plate for closing the top of said mold box, and movable between a chute-open and a chute-closed position, and control means to eifect, in succession, closure of the closure plate to segregate a charge received within the mold box, relative movement of the front and rear die plates to compress such charge, conjoint shifting of the die plates to transfer the mold box to discharging position, separation of the die plates to release the compressed block onto said block-receiving means, and return of parts to the chargereceiving position.

4. The machine defined in claim 3, wherein the block-receiving means comprises a pallet and means supporting and guiding such pallet for movement between lowered position at a level spaced below the fixed mold box bottom by appreciably more than a blocks height, and raised position substantially at the level of the fixed mold box bottom, and means operatively connected to the conjoint shifting and die-plate separating means to elevate said pallet to its raised position substantially simultaneously with operation of said means toshift the die-plate into discharging position and to separate the same to release the block, and said means being further operable to depress the pallet into its lowered position immediately thereafter.

In a machine for molding precision-interlock concrete blocks or like products, in combination, a mold box formed by complemental top,

bottom, two relatively fixed opposite sides and two relatively movable opposite sides, which latl screen n s Cater, itwo isides ccomprise idieplates shaped ::and

arranged to formacomplementali precision interlocking block faces,- meansaguiding said .die-plate sides for conjoint lateral:shiftingzmovement between retracted positionninterposedbetween said ltop. and bottom, :andzprojected position disposed beyond said top sandtbottom, drivemeans having ea definite :operating ;:cycle and poperatively' connecteduto said dieeplate sides to shift thex'same cconjointly, laterally ibetweentheir retracted and ner Loo-ordinated vvith such conjoint lateral shifting thereofkby'rsaid drive means, through a cycle commencing from initially separated charge-receiving position of said die-plate sides while retracted, then relatively together into charge-compressing position while still retracted, then, during a predeterminedportion of said operation cycle, very slightly'relatively apart, to partially, but not substantially fully, relax lbl'ock .pressure .between'. said die-plate sides, and Lfinally, when said .dieeplate :sides are in proljected position, moving them relatively further apart to release .the .block altogether lbefore zsubsequent retraction .of said die-plate wsides again. into :charge-receiving;position between said itop. and abottom.

A6. :A machine .for molding "LZCOIICIGlJS blocks or Zlike, products comprising:iatfixed mold boxabottom, a charge-conveying chute terminating thereabove, a front and a rear die plate and side plates cooperating with said bottom to form a mold box, said front and rear die plates being guided for conjoint movement between a chargereceiving position, resting upon said mold box bottom and in registry with said chute, and a discharging position beyond said mold box bottom, and being also relatively movable, a blockreceiving means at the discharging position, a closure plate for closing the top of said mold box, and movable between a chute-open and a chute-closed position, and control means to ef fect,'in succession, closure of the closure plate to segregate a charge received within the mold box, relative movement of the front and rear die plates to compress such charge, slight reverse relative movement of the front and rear die plates to relax the compression from the maximum previously obtained, conjoint shifting of the die plates in their attained relaxed but still compressed relative positions, to transfer the mold box to discharging position, relative separation of the die plates to release the compressed block onto said block-receiving means, and return of parts to the charge-receiving position.

7. In a machine for molding concrete blocks or like products, a bodily shiftab-le, open bottom mold box, means to supply a charge thereinto, means to close said bottom while it is in charging position, means to compress such charge therein into the form of a block, means to shift said mold box to a delivery position, means to open said mold box at the delivery position to free the compressed block, means at the delivery position to receive and support the freed block, and guided for movement upwardly towards the mold box and downwardly to clear the latter, means controlling movement of said block-receiving means to move the same upwardly towards the open bottom of the mold box as the latter approaches delivery position, said constrolling:meansiincluding a stop upon the blockzreceiving means and :fixedly positioned ,but -shiitable stepped stop, cooperating .tostop :the block-receiving means somewhat below'the bottom of the mold box, and means carried byxand :shiftablewith the mold 'box, to engage .and shift said stepped stop as'themold box :arrives ataits delivery position, uthe stepped stop being ar- :ranged relative toaits cooperatingstop to permit :additional upward movement of the block-re- 1 iceiving T means :into contact with the bottom :;of ,the compressed block, said mold box opening :meansbeingthereafter operable, and said blockreceiving'means being thereafter-movable down- ,wardly prior tozshiftin-g of the mold box.

a 8.,.-Inua machine for molding concrete blocks orlike:products-a front and a rear die plateland side plates cooperating as partsuof a moldzbox, said :front and rear die plates being guided for igo conjoint movement between a charge-receiving land a discharging station, and also being relaitively separable, :means interconnecting' said .die ,aplates'for suc'h:movements, said means in one position effecting closure of the mold box, and

inzanothera positionreffecting opening thereof'for release-of: the compressed product, :means to I effect such relative closure movement of the die :.-plates, means 'to effect conjoint movementmof :said Jdie.:plates,-means to efiect such releasing 730 rmovement of 1 said die plates, and means operable during conjointshifting to shift said die plates Jslightly'relative'ly, "and toiretain said interconnecting -means :jinean intermediate zrel'axed ipiosition.

9. In a machine for molding concrete blocks or like products, a front and a rear die plate and side plates cooperating as parts of a mold box, further means to complete a closable mold box, said front and rear die plates being guided for n conjoint reciprocatory movement between a charge-receiving and a discharging station, and also being relatively reciprocable, a toggle link arrangement operatively interposed between said front and rear die plates to regulate their relative movement, means toshift one die plate, and, through said toggle link connection, also the other die plate conjointly with the first, between the two stations, means to align or to break said toggle links, to compress or to release a charge within the mold box, and means to restrict the extent of breaking of the toggle links, and to retain them in such restricted position, following their compressive alignment and during conjoint shifting prior to opening or to full release of the mold box.

10. The process of molding concrete blocks or like products, of the type having interlocking or critical opposite faces, which comprises charging a mold box, compressing the charge within 60 such mold box to less than the intended block size, relaxing such compression to the intended size by relief of pressure directly against the blocks interlocking or critical face during a period to permit expansion of the block substantially to its intended size, and at the end of such period uncovering the block at a noncritical face thereof, to permit the block to emerge undistorted at its intended size.

11. The process of molding concrete blocks or 70 like products, wherein the dimensions of certain faces, less than all its faces, are critical, which comprises charging a mold box; completely closing the mold box; compressing such charge therein to less than its final size; relaxing such 75 compression but only to the extent that the asoaovt block may expand, by its inherent expansiveness,

to the final size in the critical dimensions; while like products, comprising a constrictable mold box having at least two of its opposite sides relatively movable, means operable to charge the mold box, means operable thereafter to complete the closure of the mold box, and mold box actuating mechanism operable to move said opposite sides relatively together and apart, to constrict and relax the mold box, respectively, including power means and cooperating power transfer control means operatively interconnecting said power means and said opposite sides of the mold box, said cooperating power means and power transfer control means having a definite operating cycle and comprising compression means operable during a first phase of said operating cycle to effect movement of said opposite sides, from an initial fully separated position, relatively together to constrict the mold box to a dimension smaller than the intended block dimension between such sides, retraction and holding means operable promptly thereafter, during a second phase of said operating cycle, to move said opposite sides of the mold box relatively apart to relax the mold box substantially to the intended block dimension between such sides, and, during a third phase of said operating cycle, to hold said sides in said mold-box relaxed position for a predetermined short interval, and further retraction means operable during a succeeding phase of said operating cycle to move said opposite sides further apart for discharge of the block therefrom. V

13. The machine defined in claim 12 wherein the relatively movable opposite sides of the mold "box correspond to critical faces of the block being molded therein, said machine additionally comprising means coordinated with the power transfer control means and operable in the interval after the second phase and before the fourth phase of the operating cycle of the power transfer control means to open such mold box at a side different from said opposite sides thereof.

MORTON CLARK. FRANK C. PRIESTLY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

